https://doi.org/10.1140/epje/i2010-10635-x
Regular Article
Molecular dynamics simulations of cytochrome c unfolding in AOT reverse micelles: The first steps
1
Commissariat à l’Energie Atomique, DSV/iBiTecS/SB2SM, CNRS URA2096, F-91191, Gif-sur-Yvette, France
2
Laboratoire Imagerie Paramétrique, UPMC, F-75006, Paris, France
3
CNRS, LIP UMR7623, F-75006, Paris, France
* e-mail: stephane.abel@cea.fr
Received:
26
November
2009
Accepted:
6
July
2010
Published online:
28
August
2010
This paper explores the reduced form of horse cytochrome c confined in reverse micelles (RM) of sodium bis-(2-ethylhexyl) sulfosuccinate (AOT) in isooctane by molecular dynamics simulation. RMs of two sizes were constructed at a water content of W o = [ H_2O ]/[AOT] = 5.5 and 9.1. Our results show that the protein secondary structure and the heme conformation both depend on micellar hydration. At low hydration, the protein structure and the heme moiety remain stable, whereas at high water content the protein becomes unstable and starts to unfold. At W o = 9.1 , according to the X-ray structure, conformational changes are mainly localized on protein loops and around the heme moiety, where we observe a partial opening of the heme crevice. These findings suggest that within our time window (10ns), the structural changes observed at the heme level are the first steps of the protein denaturation process, previously described experimentally in micellar solutions. In addition, a specific binding of AOT molecules to a few lysine residues of the protein was found only in the small-sized RM.
© EDP Sciences, SIF, Springer-Verlag Berlin Heidelberg, 2010